Summary/Abstract
This global study identifies 76 extreme heat waves that spanned 90 different countries over a twelve-month period between May 2023 and May 2024 and put billions of people at risk, including in densely populated areas of South and East Asia, the Sahel, and South America. In this review, the authors find that over the 12-month period, 6.3 billion people (about 78% of the global population) experienced at least 31 days of extreme heat (hotter than 90% of temperatures observed in their local area over the 1991-2020 period) that was made at least two times more likely due to human-caused climate change. Further, the authors conclude that during the 12-month study period human-caused climate change added an average of 26 days of extreme heat (on average, across all places in the world) more than there would have been in a pre-industrial period.